DE2816328A1 - Releasable electrical connector system - is formed by growing layers of dendritic crystals on metal surface and dendrites interlock to give good contact - Google Patents

Abstract

An electrical contact device consists of a substrate having a dendritic array which is grown on it and the dendrites are adapted to releasably engage corresponding dendrites on a mating surface. A typical contact comprises a conducting base plate (11) bearing a group of elastic metallic projections (13). For this purpose a suitable base plate consists of a substrate with a coating of noble metal (15) on which the dendrite crystals are formed. A second electrical contact is similarly formed of a conducting base plate (21) with closely spaced, elastic metallic projections (23). On being brought together the dendritic crystals interlock to form a good electrical connection which can, however, be readily separated. The technique is suitable for connections to LSI integrated circuits.

Description

Electrical IxontartverLinaullg and method for

Manufacture the same manufacture the same ~~~~~~ The invention relates electrical contact connections and a method for making such contact connections.

The present invention is particularly suitable for such areas of application where it is desirable to have a large number of individual, Establish releasable electrical connections. An example of such an application are the connection connections for the connection of highly integrated circuit modules on printed circuit boards and boards. One is so far always proceeded so that the individual with highly integrated circuits equipped module had a number of protruding contact pins on its underside. The printed circuit board or circuit board included a similar arrangement of sockets for receiving the contact pins of the module, if this should be connected to the card or plate. Every Such a plug connection contained in some form resilient parts, with their Help apply a corresponding contact force on the corresponding contact pin of the module is exercised. Although plug connections work satisfactorily as a result are those attached to circuit cards or circuit boards Plug connections are relatively expensive to manufacture and often take up more space as desired. In fact, it is the areas required for this, which in general limit the number of contact pins possible for each module. It would therefore be desired, a plug connection to have when on a predetermined Area on a printed circuit board or circuit board a much larger number of contact points could be provided. In order to could also be produced with highly integrated circuitry Destüc] -te modules, where a significantly larger number of input / output connections are provided could be.

The invention is particularly suitable in such areas of application in which detachable multiple connections with wesent Lich reduced costs each Connection should be created. An example of such an application is connecting the conductors of a flat multiple cable to a printed circuit board or plate. Up to now, the procedure has been to remove the individual conductors of the cable soldered to conductive elements on a so-called adapter card. These conductive elements are wired to the adapter card individual contact spring sockets connected to the adapter card, whereby for a spring socket is provided for each conductor of the cable. This spring bushing is coming while engaging with contact pins on the printed circuit board Circuit card are attached to which the electrical connections are made should. Such an arrangement works satisfactorily in itself, but it is something awkward and quite expensive. It would therefore be desirable to have a port connection between the cable and the circuit card, when using an adapter card omitted, and the previously required spring bushing for each connection point ceases to exist. Among other things, this would result in a substantial reduction in costs for the final connection.

Ls could be # any other examples, but so far they should given iiins.eise suffice that there is a need for electrical contact connections that cost less and take up less space.

Summary of the Invention The object of the invention is therefore to provide a create new and improved electrical contact for contact connections, which provides good electrical contact at a lower cost per connection point, has only a very small constant resistance to contact and only a small one Forces needed for an I, old of the contact connection. It should in particular may not be required for multiple contact connections for each connection point having to provide a separate spring bushing.

According to the present invention there is an electrical contact connection created by having a contact surface or a contact surface Number of very small elastic metallic projections produced by the fact that dendrites consisting of metallic crystals grow on it. A severable electrical connection is made by making the dendritic crystals brings into interlocking engagement with just such dendritic contacts. This wedge-like interlocking engagement is practically self-locking. To the Maintaining this electrical connection is therefore only a very small one Force required. The self-cleaning effect of the dendritic crystals at Engagement with each other and the contact forces generated by the wedge-shaped engagement effect result in a reliable connection with low contact resistance. The dendritic metallic crystals are generated on the contact surface by having them Contact area at a higher than normal current density with a plating solution that has a lower concentration of metal ions having.

The invention will now play on the basis of execution sbei in connection described in detail with the accompanying drawings.

In the drawings: FIG. 1 shows a greatly enlarged view of a Pair of dendritic contacts constructed according to the invention, FIG. 2 is a plan view on a circuit board provided with a printed circuit, on which various, modules provided with highly integrated circuits are attached via multi-conductor flat cables of different widths are connected, Fig. 3 is a side view of the in Fig. The circuit board shown in FIG. 2; FIG. 4 is an enlarged sectional view of a part the circuit card shown in Fig. 2 and a greatly enlarged side view of part of one of the circuit modules in Fig. 2, together with an enlarged View of some of the related dendritic contacts used to make the electrical sciialt connections, Fig. 5 is an exploded view View of the fastening of the flat cables to the circuit board in FIGS. 2, 6 an enlarged view of one of the flat cables in FIG. 2 from below with the dendritic Contacts for making the electrical connections to the circuit board in FIG. 2, FIG. 7 is an enlarged view of a corner of the circuit card shown in FIG to show how the dendritic contacts located thereon with the in Fig. 6 cooperate shown cable contacts and Fign. 8 and 9 scanning electron microscope photographs to show the dendritic contact structure on a greatly enlarged scale.

Description of the preferred embodiment of the invention In Fig. 1 is, on a greatly enlarged scale, a pair of cooperating dendritic contacts shown shortly before contact. In particular, Fig. 1 shows a first dendritic contact 10, which consists of a conductive base plate 11 and a group or a tuft 12 of the smallest, closely spaced elastic, metallic projections 13 is formed on the conductive base plate 11 by dendritic growth conductive metallic crystals is formed. The conductive base plate 11 is made a conductive element or substrate 14 on which a thin layer 15 of a noble metal has been applied in the surface area in which an electrical Contact should be established. the metallic protrusions or dendritic crystals 13, which are also made of a noble metal on the exposed surface of this thin layer 15 under such conditions formed or grown up that promote the formation of dendritic structures.

Furthermore, a second electrical contact 20 is shown, which from a conductive base plate 2t and a group 22 of closely spaced, very small ones elastic metallic projections 23, which on the base plate 21 through the dendritic growth of crystals made of a conductive metal is formed. The base plate 21 consists of a conductive element or Substrate 24 on which a thin surface layer 25 of a noble metal on the one Surface is applied to which an electrical contact is to be made. The metallic protrusions or dendritic crystals 23 are also made of a precious metal and will be on the exposed surface of this thin layer 25 generated by an electrolytic process carried out under conditions that promote the formation of dendritic structures.

The two electrical contacts 10 and 20 when they cooperate as shown in FIG are arranged, form a separable electrical connection. The electric Connection is made by making the metallic dendritic crystals 13 of the first conductive base plate 11 with the metallic protrusions 23 of the second brings conductive base plate 021 into a mutually wedging engagement.

The two similarly structured contacts come in together Engagement, then the metallic projections 13 and 23 slide past each other, and there is a kind of wedge effect that eventually occurs on the various crystal surfaces leads to relatively high stresses. this will from accompanied by a wiping or rubbing effect of metal on metal, so that there is an intimate metallic contact and a gas-tight connection at many points results.

The excess of contact points represents a high level of reliability and a low contact resistance. Any dust particles that may be present are thereby practically pushed aside and thus affect the quality the electrical connection is not.

It is important to point out that there is mutual interference of the metallic projections 13 and 23 with each other only very little by use Forces is achieved. The metallic protrusions 13 and 23 slide relatively easily past each other After making the connection, the construction is quite stable, because the wedged metal protrusions have a kind of self-locking Have property so that only a very small force to maintain the Contact connection is required. Because of the dendritic structure of the contacts there is also little misalignment or tolerance error longitudinally one of the spatial axes is possible without adversely affecting the contact properties to be influenced.

The selection of the for the dendritic projections 13 and 23 and for the surface layers 15 and 25 of the metal used will be discussed individually. A good example of a metal that is suitable for both purposes is palladium. the Baseplates or substrates 14 and 24 are typically made of copper or some other metal commonly used for electrical conductors. Assuming that Palladium is selected, the surface layers 15 and 25: by electrolytic Deposition of a thin layer of palladium on the substrate surface below such conditions formed in which the formation of dendritic structures is not funded. Then the metallic projections 13 and 23 on the exposed surfaces of layers 15 and 25 by electrolytic Deposition of palladium grown under such conditions that the formation promote dendritic structures.

The protrusions 13 and 23 made in this way are quite small. The greatest height of one of these projections (dimension fl in Fig. 1) is in Range between 0.1 to 0.15 mm.

In the example application shown here, the width is of the entire cluster of dendritic protrusions for a single contact (dimension D in Fig. 1) between 0.5 and 0.8 mm. As indicated in Fig. 1, the individual such a tuft-forming projections of different sizes and different Shape and are mixed with each other more or less irregularly.

Figs. 8 and 9 show produced with a scanning electron microscope Recordings of dendritic arrays actually produced from palladium 12 or 22, which have been manufactured according to a process to be described, the dendritic projections 13 or 23 shown there opposite their actual size shown enlarged thousands of times. A typical arrangement 12 has between 3,000 and 20,000 dendritic protrusions per square millimeter on, the actual number in each case being a function of the particular Area of application is. The height of the dendritic protrusions is between 10 and a maximum of 150 micrometers. Also, the aspect ratio is dendritic Protrusions, d. H. the height of a protrusion divided by the largest diameter between a minimum value of 4 and a maximum value of 10. In addition, this is Outline ratio of an array 12, i. H. the total area for all protrusions in a Arrangement, for example, through vertical illumination the arrangement is determined from above, divided by the area of the conductive base plate, on which the array of projections is formed, between 0.10 and 0.39.

In connection with FIGS. 2 and 3 are intended to be an exemplary application such dendritic electrical contacts, such as those shown in FIG. 1, for example are, for new and improved electrical multiple contact connections for electronic Devices are represented. Figs. Figures 2 and 3 show one with a printed circuit board provided circuit board 30 on which a number of large scale integrated circuits provided circuit modules are attached. These modules 31, 32 and 33 are open of circuit board 30 is shown. A fourth module 34 (Fig. 4) can be at the location 35 of the Card 30 are attached, but is not shown in Fig. 2, so that an arrangement 36 of small dendritic contacts on the circuit board 30 for making of electrical multiple clocks with the LSI module 34 can be shown.

A similar arrangement 37 (Fig. 4) of small dendritic contacts is on the underside of the LSI module 34 for a corresponding contact connection provided with the corresponding dendritic contacts in the arrangement 36. at 38 are bores in the circuit card 30 for receiving guide pins 39 (Fig. 4) protruding from the bottom of an LSI # 1 module 34.

In the course of the description, it is not intended to be between circuit card and circuit board can be distinguished. Both expressions refer to the same type of construction and should therefore be identical or interchangeable be used with each other.

Each dendritic contact 36a, 36b, 36c that is on the circuit board The arrangement 36 located there is constructed in the same way as that shown in FIG. 1 Contact 10. Any dendritic contact 37a, 37b, 37c, etc., attached to the module th arrangement 37 is constructed in the same way as that shown in FIG. 1 and in context contact described therewith 20.

Multiple electrical contact connections are therefore in the way made that the module 34 is pushed towards the circuit board 30, so that the metallic projections of the associated contacts with one another an interlocking, wedging engagement.

For example, the arrangement 36 shown in FIG. 2 as a whole 400 individual dendritic contacts on a square surface 2.54 x 2.54 cm are attached. In this case, the conductive substrate can be used for each contact takes the form of a circular metallization with a diameter of 0.5 mm and distances of 1.27 mm between the centers of adjacent metallizations accept. The associated arrangement on the underside of the module 34 would of course have the same dimensions.

This number of 400 contact connections should be with the fewer compared to 100 (generally 70-90) contacts using previously common methods can be accommodated on an area of the same size.

As indicated in Fig. 4, the circuit board 30 is a multilayer circuit board with printed circuit. Inner layers of copper foil 40 and 41 are located between layers 42, 43 and 44 made of non-conductive material. On the top surface of the topmost insulating layer 42 can be another layer to be cast down from copper. It can also be on the surface below of the lower insulating layer 44 also has one another super layer be attached. The copper layers are used for representation in a known manner etched electrical conduction pattern, with the inner layers 40 and 41 must of course be appropriately etched before applying the insulating layers. The contact surfaces on which the dendritic crystals are grown will become formed in the same way. In other words, the contact surfaces or are conductive Substrates for contacts 36a, 3Gb, 36c, etc. on top surface the insulating layer 42 is formed by initially a thin, made of copper Layer deposited there and the unneeded parts of this copper layer aLgec, be tzt.

The contact surface of the contact 36b is, for example, with a Conductor connected in the copper foil layer 40, while the contact surface for the Contact 36c electrically connected to a conductor in the copper foil layer 41 is. This is achieved by the contact surfaces lying on the surface and small-diameter holes through the corresponding insulating layers which are then filled with conductive material. That conductive material constituting the electrical connection for pad 36b is shown at 45, while that is the conductive connection for the contact surface Conductive material representative of 36c is shown at 46. These connections between Contact surface and internal copper foil are made before the Contact surfaces the dendritic crystals are grown on. The electric Connection for the contact surface of the contact 36a is made with the help of the on the insulating layer 142 lying copper layer, but this is for a simplified illustration Not shown.

Multiple electrical connections for the other modules 31 to 33 are provided in the same way as just described for module 34 has been.

As in FIGS. 2 and 3, the modules 31 to 34 are shown on the Circuit card 30 by means of elongated strips 47, which are attached to the circuit card 30 are attached, as well as held by transverse strips 48, the ends of which on the strips 47 are screwed on with small screws 49. As shown in Fig. 3, the Strips 48 on the top of the modules so that they are shaken by shocks or vibration cannot detach itself from the circuit board 30. Through this mechanical Arrangement, the metallic projections of the associated dendritic Contacts held in wedging engagement with one another. The ones through the ledges The force exerted is more of a holding force than a pressing force. she has hence a relatively small value.

Figs. Figures 2 and 3 also show the use of dendritic contacts for connecting multiple flat cables to the circuit board or board. The card-side Ends of four different flat cables 50, 51, 52 and 53 are shown in Fig.

shown. As seen from the view in Fig. 5, these are flat cables 50 to 53 near the edge of the circuit board 30 with U-shaped pressure pads 54 to 57 and 1 corresponding U-shaped brackets 58 to 61 held.

The pressure pads 54 to 57 are made of rubber or another deformable, non-conductive material.

As shown in the bottom view in Fig. 6, each of the Flat cables, such as the flat cable 50 shown there, from a large number of flat cables electrical conductors 62 arranged side by side and between two layers made of non-conductive material are included. The conductors 62 can, for example be thin strips of copper foil, those in a pliable plastic material are embedded.

Near the end of each cable are a pair of guide pin holes 63 provided, which serve to accommodate corresponding guide pins 64, which are slightly protrude beyond the surface of the circuit board 30. Fig. 7 shows an enlarged View of the part of the circuit board 30 to which the flat cable 50 is connected is. This figure is on the same scale as the enlarged view of the flat cable 50 in FIG. 6.

A multiple contact connection for connecting the individual conductors of the flat cable 50 with a corresponding group of conductors on the printed Circuit board is made by forming a linear array of dendritic contacts directly on the flat cable 50 and further by forming a corresponding one linear arrangement of dendritic contacts near the edge of the circuit board 30 manufactured. In particular, there are small electrical contact areas at the end of the cable 50 65 formed by the fact that the insulating material lying over the conductors 62 is either scraped off or otherwise removed. A thin surface coating made of a precious metal is then applied galvanically to each of the exposed contact surfaces 65, whereupon on this surface layer of each of these contact surfaces the dendritic metallic protrusions are grown.

For the sake of simplicity, these dendritic crystals are shown in Fig. 6 not shown.

Matching dendritic contacts are on a corresponding Arrangement of small contact areas 66 formed on circuit board 30 like this Fig. 7 shows. Each of the contact surfaces 66 consists of a piece of copper foil that is attached to the surface of the circuit board 30.

In either case, the copper foil is on the top surface the contact surface is a layer of a noble metal galvanic applied, whereupon a tuft of dendritic on the surface of the precious metal coating Metal protrusions is grown. Again, in the illustration of Fig.

7 the dendritic projections are omitted for the sake of simplicity.

The flat cable 50 is attached to the circuit board 30 by that the cable 50 shown for example in FIG. 6 in that shown in FIG Turns the position around and places the holes 63 for the guide pins 64 on them. The pressure pad 54 is then placed over the overlapping sections of the flat cable 50 and the circuit board 30, as shown in Fig. 3, pushed on, whereupon the spring clip 58 is pushed over the pressure pad 54 and into the position shown in FIG. 3 position shown is brought. In this way, then, the dendritic protrusions become of the contact surfaces 65 of the cable 50 in wedging engagement with the dendritic ones Projections of the corresponding contact areas 66 on the circuit board 30 in FIG Engagement held.

Each of the contact areas 66 on the circuit board 30 is provided with a another conductor 67 made of copper foil on Her printed circuit board tied together. For a multilayer circuit board, individual conductors can be used 67 Wuf the surface of the circuit board 30 lie while others these conductors The circuit board 30 may be contained inside at different levels. In these cases electrical connections are made by drilling holes formed small diameter, which, as described in connection with Fig. 4, be filled with a conductive material. The individual contact surfaces 66 on the circuit board 30 have the same dimensions as the contact areas 65 on flat cable 50. The width of any such contact surface 65 or 66 is the same as that Width of one of the conductors 62 of the flat cable, this width can be, for example, 0.254 ma. The length of each contact area 65 or 66 can be about twice as large, in other words about 0.5 mm.

The connection connections for the other flat cables 51 to 53 are constructed in the same way as for the flat cable 50, the only difference being that accordingly the different number of electrical conductors in the other flat cables 51 to 53 different numbers of dendritic contacts are provided.

As can be seen from the examples described so far, can Electrical contacts constructed according to the invention for the construction of detachable multiple contact connections that take up very little space. There are none for each connection point separate spring arrangements are required, and the contacts can be kept very small will. The space saved in this way can be achieved with the contacting described so far between the LSI module and the circuit board to use that for a given area a much larger number of independent electrical connections can be produced.

Also of considerable importance is the fact that the cost for an electrical multiple contact connection according to the invention is much lower can be maintained than with previously known multiple contact connections. this results in particular from the fact that for the various connection points the individual Contact springs and contact pins can be omitted and that also when There is no need for any work necessary to construct the contact connections. When using of flat cables there is also a considerable saving in that the cable to any length and for any number of conductors rightly can be cut. The number of contacts placed on the circuit board can be easily changed for any number of conductors in the flat cable.

The manufacture of an electrical constructed according to the invention Contact will now be described in detail, the contact 10 in Fig. 1 is intended to serve as a model for the description. In this regard, the small metallic protrusions 13 that actually make the electrical connection, preferably consist of a metal that is both electrically conductive, mechanically is elastic and is not disadvantageous at room temperature in normal surroundings changes. A disadvantageous change should mean, for example, that the exposed The surface of the metal becomes covered with an adherent corrosion film, such as an oxide layer or a sulfide layer or the like. With springy or elastic is supposed to be here be meant that the metal of the dendritic projections after loosening the contact connection resumes its original shape without permanent deformation. Hence the metallic projections 13 resilient, so that they are in an interlocking Engagement and a wedging contact with an opposing contact deform something of the same kind and immediately restore their original shape and position accept if the associated contact is removed.

The metallic projections exist in accordance with these requirements 13 preferably made of a noble metal, which consists of palladium, platinum, rhodium, Iridium, ruthenium or osmium existing group is selected. Any of these metals is electrically conductive, does not tarnish at room temperature and can be used during manufacture obtain mechanical elasticity. Because of the slightly lower cost, it is palladium probably the cheapest choice.

The dendritically grown structures, shown here as metallic Projections 13 shown are sometimes referred to as dendrites. You can different depending on the electroplating parameters under which they are grown Take shape. Needle-shaped or needle-shaped contacts are suitable for making contacts Spearhead-shaped dendritic shapes, such as those shown in FIG. 1, for example are, probably the best. A slightly different type that can also be used for some purposes Seems to be well suited, is obtained by # that one at the tip of the needle-like Structures small mushroom-like heads can arise. This gives you an even better one self-retaining or self-locking behavior, if this is desired.

The thin galvanic coating 15 is preferably also made of a precious metal. The purpose of layer 15 is to provide a dense compact, to form pore-free corrosion-resistant surface on which the dendritic protrusions 13 can be grown up. This results in a better connection, corrosion is prevented, as well as undesirable galvanic changes. This layer 15 can use any of the above for the dendritic projections 13 be made of metals. For layer 15, however, it is not necessary that the metal is elastic. This means that an inelastic precious metal such as e.g. gold, can be used for layer 15.

The conductive element or substrate 14 is at least one Part of the electrical circuit or wiring to which contact is made shall be. This conductive element can therefore take the form of a wire, pin, Stick, a contact tab, a plate, a film or the like. Accept. Normally the substrate 14 is made of copper, although it is some other metal can exist normally used for electrical conductors will. Should the substrate 14 consist of a non-tarnishing noble metal that has the appropriate surface properties, then this can be done by electroplating applied thin surface layer 15 are omitted.

The dendritic structures or protrusions 13 are preferred galvanically generated under unusual operating conditions. During normal galvanic In general, great care is taken to prevent the manufacture of coatings related to the emergence of dendritic structures. For the purposes of the invention will be deliberately violates the normal and customary procedural rules during electroplating, in order to promote the growth of dendritic structures. In particular, be the dendritic structures or projections 13 produced according to the invention by that the electroplating is carried out at a higher than normal current density becomes, while the electrolytic solution has a lower than usual concentration of metal ions. Normal working conditions should be characterized by such values that provide a dense, compact, pore-free surface.

In contrast, the surface layer 15 becomes electrolytically beneath normal working conditions are generated in which the formation of dendritic structures is not funded.

One for the purposes of the invention, i.e. for growing dendritic ones Structures made of palladium, suitable electroplating, solution consists of one Solution of water (H20), ammonia (NH3), ammonium chloride (NH4Cl) and palladoammine chloride (Pd (NH3) 2Cl2). The concentrations of the composition that are particularly useful are in the area pd + 2 at 20 to 50 millimolar Cl at 2 to 5 molar NH3 for a pH value in the range between 9.0 and 10.5.

By comparison, a normal concentration of palladium ions would be on the order of 100 millimolar compared to that given above Range from 20 to 50 millimolar.

Suppose the surface layer 15 has already become electrolytic generated, then the object on which the dendritic made of palladium Structures are meant to be grown in an electrolytic bath with the above given values introduced and electrically connected in such a way that the object forms the cathode for electroplating. Any conductive surface of the object on which no dendritic crystals are to be grown, is prior to introduction coated in the galvanic bath with a thin layer of insulating material. Afterward is between the cathode formed by the object and a likewise in When the electrode was immersed in the bath, a direct voltage was connected to it, which acts as an anode. Then a higher current than usual is passed through the galvanic bath, so that on the exposed surface of the object dendritic metallic Growing up ledges.

For this purpose, a current density in the order of 100 mA / cm2 found useful. The normal current density for galvanic generation a palladium layer without the growth of dendritic structures lies in the Of the order of 10 mA / cra2. In both cases these values are the current density measured on the cathode surface.

It is desirable to use several separate contact areas at the same time To let dendritic protrusions grow, then it is necessary that each of these Areas during the production of the galvanic over train with the negative terminal connected to a DC power source. In the case of that shown in FIG Flat cable this can be done in such a way that the distal ends of the conductors 62 be connected to the negative terminal of the direct current source and that the The end with the contact surfaces 65 is immersed in the galvanic bath. For multiple contact surfaces on a circuit board such as Fig. 4 or Fig. 7, a simultaneous Achieve dendritic growth in that one formed by copper foil Connections between the contact surfaces for interconnection can exist and that these connections are made after the dendritic protrusions have grown on etches the desired contact surfaces.

Figs. d;, 8 and 9 show photographs of actually made dendritic ones Structures such as those described above by electroplating with palladium Way to be generated.

These photographs were taken with a scanning electron microscope, and the dendritic structures shown there are opposite to their actual ones Size shown roughly 1000 times coarser.

According to the applicant's knowledge and experience, the galvanic production of dendritic structures under the just described, novel operating conditions represent the previously preferred method. However, this is not as an implied limitation on the process in making dendritic ones Structures to be understood, as there are also other methods with which such structures manufactured can be. Such methods are for example electroless processes in which the reduction is done chemically without the use of electrodes or an electric current, electroforming and chemical deposition from the vapor phase.

Claims (21)

PATEN TA N SPRÜCHE 1. Electrical contact connection, characterized in that that each contact (10, 20; 11, 21) consists of a base plate (14, 24) and one on it located dendritic arrangement is made with a correspondingly constructed similar contact is releasably engageable. 2. Electrical contact connection according to claim 1, characterized in that that the dendritic arrangement consists of a group of dendritic projections (13, 23), which, viewed from the base plate, extend away from the latter. 3. Electrical contact connections according to claim 2, characterized in that that the majority of the projections (13, 23) is shaped like a needle. 4. Electrical contact connection according to claim 1 and 2, characterized in that that the majority of the projections (13, 23) is shaped like a spearhead. 5. Electrical contact connection according to claim 2, characterized in that that the projections have a dendritic structure. 6. Electrical contact connection according to claim 2, characterized in that that the protrusions are dendrites. 7. Electrical contact connection according to claim 2, characterized in that that the projections are elastically deformable. 8. Electrical contact connection according to claim 2, characterized in that that the projections are resilient. 9. Electrical contact connection according to claim 2, characterized in that that the dimensions of the projections are in the sub-millimeter range. 10. Electrical contact connection according to claim 2, characterized in that that the projections are made of a noble metal. 11. Electrical contact connection according to one or more of the claims 1 to 9, characterized in that the dendritic projections (13, 23) from one Composed of the palladium, platinum, rhodium, iridium, and ruthenium metal Osmium-containing group is selected. 12. Electrical contact connection according to claim 11, characterized in that that the dendritic projections are made of a material that is at room temperature does not form an adherent corrosion coating in a normal room atmosphere. 13. Electrical contact connection according to claim 12, characterized in that that the base plate (14, 24) on its surface on which the dendritic projections to be produced has a thin layer of a noble metal. 14. Electrical contact connection according to claim 1 and 2, characterized in that that the projections are produced by electroplating under such conditions that formation Promote dendritic structures on the surface to be electroplated. 15. Electrical contact connection according to claim 14, characterized in that that the projections galvanically at a higher than the usual current density with a bath solution that has a lower than the usual concentration of metal ions. 16. Electrical contact connection according to claim 1 or 2, characterized in that that the projections have an aspect ratio between 4 and 10. 17. Electrical contact connection according to claim 2, characterized in that that the projections have an outline ratio with respect to the base plate of at least 0.10. 18. Electrical contact connection according to claim 17, characterized in that that the outline ratio in relation to the base plate is between 0.10 and 0.39 lies. 19. Electrical contact connection according to one of the preceding claims, characterized in that the number of dendritic projections per square millimeter the area of the base plate is between 3,000 and 20,000. 20. Electrical contact connection according to claim 1, characterized in that that the load capacity is at least 10 amps per square millimeter of the conductive surface the base plate is. 21. Method for making the contacts of an electrical contact connection according to one or more of claims 1 to 20, characterized by the following Method steps: immersing the conductive element (11, 21) which forms part of the Contact is to form in a galvanic bath, the bath solution of which is smaller than has the usual concentration of metal ions, connect a DC power supply between the conductive element and an electrode immersed in the bath, and Operation of the electroplating bath with a higher than the usual current density.